Anatomy of the Slug. 337 



they surround it. In them can be distinguished two kinds of 

 cells, very fine granular cells, with large granular nuclei and 

 distinct nucleoli, some of which cells are vacuolated, and smaller 

 cells, which stain more deeply. From each gland a duct runs 

 up to open into the oesophagus (Fig. 5) just before it leaves the 

 buccal mass. 



The Liver (Figs. 8 to 12) is a large organ situated about the 

 middle of the visceral mass, and more or less surrounding the 

 hermaphrodite and albumen glands, the stomach and the intes- 

 tine. It consists of a large number of caeca bound together 

 by connective tissue. The lumina of the caeca are bounded by 

 cells, which are probably secretory, and contain masses of small 

 brown-stained particles. 



The Nervous System. 



There do not seem to be any notable differences in the struc- 

 ture of the nervous system of this species from that of other 

 forms. 



The Cerebral ganglia (Figs. 7 and 8) are two large pyriform 

 masses lying on either side of the oesophagus, at their posterior 

 ends swelling out dorsally to lie right across it, so as to form, 

 with the pedal and viscero pleural ganglia, a collar round the 

 oesophagus (Fig. 7), The cerebral commissure (Fig. 7) is short, 

 connecting the two ganglia across the oesophagus. Anteriorly 

 two short buccal nerves run forwards, and just beside the 

 salivary ducts, from the two buccal ganglia (Fig. G). which are 

 connected by the buccal commissure. Nerves from the buccal 

 ganglia supply the buccal mass. The tentacular nerves are very 

 large, and arise from the outer sides of the cerebral ganglia 

 towards their anterior ends. (Fig. 7.) Labial nerves also arise 

 from the cerebral ganglia, and far forward give rise to labial 

 ganglia. 



The Pedal and Visceropleural ganglia (Figs. 7 and 8) lie 

 very close together, forming the sub-oesophageal ganglionio 

 mass. The viscero-pleural ganglia are situated slightly dorso- 

 lateral to the pedal ganglia. The ganglia are connected by 

 commissures, and also there are the cerebro-pedal, cerebro- 

 visceral, etc., connectives, as in other forms. From the pedal 



